The study of quasicrystalline and similar phases is performed by X-ray emission spectroscopy (XES) with an emphasis on the parameters of the density of states near the Fermi energy. Particular attention is paid to the characteristics of the density of states of Al3p obtained in a detailed study of Al–Cu(–Fe) compounds. The average binding energy due to the Al3p states and the second moment of their distribution are analyzed.
The results demonstrate that the contribution of the localization of 3p states of Al, according to the Hume-Rothery mechanism, to the stability of the compound is maximal for the icosahedral structure. The enhancement of sp-d hybridization of Al with transition metals in the presence of icosahedral order is also shown. The relationship between the pseudogap depth near the Fermi energy and the apparent surface energy of the samples is confirmed.
X-ray photoelectron spectroscopy has an advantage over other methods, such as photoemission spectroscopy, due to its sensitivity to the chemical nature of the atom and the orbital nature of the electron state. This is especially important for aluminum-based quasicrystals and approximants, where the energy resolution in measuring the density of states of Al 3p does not exceed 0.4 eV.
The study of the electronic structure of Al–Cu–Fe compounds, in particular the density of states (DS) of Al 3p, is key to understanding their stability and surface properties. Analysis of the DS of Al 3p obtained by X-ray photoelectron spectroscopy and theoretical calculations demonstrates significant differences between the crystalline and quasi-crystalline phases. In quasicrystals, broadening and a shift of the Al 3p peak toward higher binding energies are observed, indicating a change in the local environment of aluminum atoms and hybridization of electronic states.
A correlation was found between the Al 3p DS near the Fermi level and the formation energy of the Al–Cu–Fe phases. An increase in the Al 3p DS near the Fermi level is associated with an increase in the stability of the quasi-crystalline phase. Also, changes in the Al 3p DS affect the visible surface energy of the quasicrystals, which determines their wettability and adhesive properties. The results obtained allow us to establish a relationship between the electronic structure, stability, and surface properties of Al–Cu–Fe quasicrystals, which is important for the development of new materials with specified characteristics.
Author:Esther Belin-Ferré, Jean-Marie Dubois, Vincent Fournée, Pierre Brunet, Daniel J Sordelet, LM Zhang
Institute:LCPMR UMR 7614 and GDR CINQ, 11 rue Pierre et Marie Curie, F-75231 Paris, France, LSG2M UMR 7584 and GDR CINQ, EMN, Parc Sorupt, F-54042 Nancy, France, Metals Engineering, Ames Laboratory, Ames, Iowa 50011, USA, Department of Materials Science, Dalian University of Technology, Dalian 116023, P.R. China